Examples of sensors used in automated robots to detect obstacles, or sensors used to detect people include laser rangefinders (LRF).
Laser rangefinders calculate the distance to a target object by measuring the time it takes emitted laser light to reach the target object and then return after reflecting off the target object. Laser rangefinders horizontally and vertically vary the direction in which laser light is emitted to measure distance to a target object, over an entire given area (hereinafter also referred to as “scanning area”).
Such a laser rangefinder has been proposed that uses a motor to rotate a structure in which a light emission optical system for emitting light from the light source out of the laser rangefinder is integrated with a light reception optical system for receiving reflected light reflected from the target object (for example, see Patent Literature (PTL) 1). The laser rangefinder obtains distance information from the phase difference between the reflected light from the target object and the emitted light. The laser rangefinder further uses the motor to rotate a plate having a plurality of slits at predetermined intervals, and obtains rotation angle information using the pulse count detected by a photo interrupter disposed on the rotational path of the slit plate. This allows the laser rangefinder to calculate two-dimensional distance information.